Add Docker setup with nginx for serving the game

- Add Dockerfile using nginx:alpine base image
- Add docker-compose.yml for easy container management
- Add nginx.conf with minimal configuration and gzip compression
- Service renamed to 'ui' for better naming convention

docker-compose.yml

@@ -0,0 +1,7 @@
+name: threejs-test
+
+services:
+  ui:
+    build: .
+    restart: unless-stopped
+